Prior applications filed by an entity engaged in joint research with the owner of the present application describe neuromodulation methods using electrodes positioned in a blood vessel. The electrodes disposed inside the blood vessel are energized to stimulate or otherwise modulate nerve fibers or other nervous system targets located outside the blood vessel. Those prior applications include U.S. Publication No. 2007/0255379, entitled Intravascular Device for Neuromodulation, U.S. 2010/0023088, entitled System and Method for Transvascularly Stimulating Contents of the Carotid Sheath, U.S. application Ser. No. 13/281,399, entitled Intravascular Electrodes and Anchoring Devices for Transvascular Stimulation, International Application PCT/US12/35712, entitled Neuromodulation Systems and Methods for Treating Acute Heart Failure Syndromes, and U.S. application Ser. No. 13/547,031 entitled System and Method for Acute Neuromodulation, filed Jul. 11, 2012. Each of these applications is attached in the Appendix and is fully incorporated herein by reference. The latter application describes a system which may be used for hemodynamic control in the acute hospital care setting, by transvascularly directing therapeutic stimulus to parasympathetic nerves and/or sympathetic cardiac nerves using an electrode array positioned in the superior vena cava (SVC).
Proper placement of intravascular electrodes is essential for neuromodulation. The electrodes must be positioned to capture the target nerve fibers, while avoiding collateral stimulation of non-target nerve fibers. Mapping procedures are typically performed at the time of electrode placement to identify the optimal electrode location. Mapping can be manually controlled by the clinician or automatically controlled by the neuromodulation system. During mapping, different electrodes, combinations of electrodes, or arrays can be independently energized while the target response to the stimulus is monitored. For stimulation relating to cardiac or hemodynamic function, parameters such as heart rate, blood pressure, venticular inotropy and/or cardiac output might be monitored. In some cases mapping includes additional steps of repositioning the electrode carrying member so as to allow additional electrode sites to be sampled. The mapping process is performed until the optimal electrode or combination of electrodes for the desired therapy array is identified.
Referenced prior application Ser. No. 13/547,031 describes a neuromodulation system that may be used for hemodynamic control in the acute hospital care setting, by transvascularly directing therapeutic stimulus to parasympathetic nerves and/or sympathetic cardiac nerves using an electrode array positioned in the SVC. That system includes a control system suitable for carrying out the therapy. The neuromodulation system includes a therapeutic catheter having therapeutic elements such as electrode arrays, and optionally, patient and system diagnostic elements; sensors (e.g. pressure sensors, flow sensors, other hemodynamic sensors, other patient condition sensors, and system condition sensors such as position sensors, system connection sensors or other system error condition monitoring sensors). The neuromodulation system also includes an external stimulator, (also referred to here as a neuromodulator or “NM”). The external stimulator has a clinician user interface and functions to provide therapeutic stimulation outputs to the therapeutic catheter; therapeutic outputs that are dynamically controlled in a closed-loop manner in response to information from one or more of the diagnostic elements, or may be controlled manually by the clinician. The diagnostic elements include sensors for patient hemodynamic feedback such as heart rate (HR), blood pressure (BP), and other suitable sensed or derived hemodynamic parameters (which may include central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), cardiac index, derivations of vascular resistance, cardiac output, and cardiac filling pressures); sensors and/or analyzers to determine other patient conditions such as cardiac arrhythmia, cardiac capture, respiration, or patient movement; and other sensors and analyzers to monitor system conditions for error, malfunction or unsafe state (referred to as “safety monitoring”) that should be indicated to the clinician and/or result in termination of stimulation.
During use of such systems for hemodynamic control, the electrodes are positioned at the distal end of an intravascular catheter (referenced here as the “neurocatheter” or “NC”) percutaneously delivered to the target stimulation site within the SVC. The electrodes are placed against the SVC wall in order to transvascularly stimulate parasympathetic and sympathetic cardiac nerves. Prior studies have identified areas on the posterior wall of the mid-to-cranial SVC, between the brachiocephalic junction and right atrium, where both parasympathetic and sympathetic nerves can be electrically stimulated. The use of an array of electrodes on the NC allows general placement into a target region of the SVC without a requirement for precise placement. The NC electrode array only needs to be placed into this general SVC target region to facilitate neuromodulation system function. This region can be defined by both a longitudinal range of the SVC, and by a circumferential range of the SVC (see FIGS. 1A and 1B). Previous disclosures have identified the preferred longitudinal range as the mid-to-cranial SVC, and preferred circumferential range along the posterior side of the SVC.
It is known that accessing the human SVC using the widely accepted, standard percutaneous procedure, especially from venous access sites such as the internal jugular, subclavian or femoral veins is a simple and straightforward technique, in which a variety of clinicians are proficient. In order to provide for both ease-of-use in the acute hospital setting and allow for positioning without the use of imaging, such as fluoroscopy, the NC contains an “array” of electrodes to provide a coverage area for capture of target cardiac nerves. All of the electrodes in the array can then be connected to the NM, and the NM can then “select” the desired anodes and cathodes by means of electronic switching circuitry in its response mapping function.